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June 23, 2012 Strange exception using threads | ||||
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I am using a secondary thread to send messages to it so it can print those messages. import std.stdio; import std.concurrency; void main() { auto low = 0, high = 10; auto tid = spawn(&writer); foreach(i; low..high) { writeln("Main thread: ", i); tid.send(tid, i); } } void writer() { while( true ) { receive( (Tid id, int i) { writeln("Secondary thread: ", i); } ); } } This is the result: Main thread: 0 Main thread: 1 Main thread: 2 Main thread: 3 Main thread: 4 Main thread: 5 Main thread: 6 Main thread: 7 Main thread: 8 Main thread: 9 Secondary thread: 0 Secondary thread: 1 Secondary thread: 2 Secondary thread: 3 Secondary thread: 4 Secondary thread: 5 Secondary thread: 6 Secondary thread: 7 Secondary thread: 8 Secondary thread: 9 std.concurrency.OwnerTerminated@std/concurrency.d(248): Owner terminated ---------------- /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(bool std.concurrency.MessageBox.get!(void function(std.concurrency.Tid, int)*).get(scope void function(std.concurrency.Tid, int)*).bool onControlMsg(ref std.concurrency.Message)+0x2a) [0x437016] /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(bool std.concurrency.MessageBox.get!(void function(std.concurrency.Tid, int)*).get(scope void function(std.concurrency.Tid, int)*).bool scan(ref std.concurrency.List!(std.concurrency.Message).List)+0x68) [0x437084] /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(bool std.concurrency.MessageBox.get!(void function(std.concurrency.Tid, int)*).get(scope void function(std.concurrency.Tid, int)*)+0x88) [0x436c20] /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(void std.concurrency.receive!(void function(std.concurrency.Tid, int)*).receive(void function(std.concurrency.Tid, int)*)+0x32) [0x436b86] /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(void main.writer()+0x13) [0x43066b] /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(_D3std11concurrency11__T6_spawnZ6_spawnFbPFZvZS3std11concurrency3Tid4execMFZv+0x45) [0x430941] /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(void core.thread.Thread.run()+0x2a) [0x4470fe] /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(thread_entryPoint+0xf3) [0x446e97] The program runs correctly but then boom! Does anyone know why? |
June 23, 2012 Re: Strange exception using threads | ||||
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Posted in reply to Minas Mina | On Sat, 23 Jun 2012 18:05:47 +0200, Minas Mina <minas_mina1990@hotmail.co.uk> wrote:
> I am using a secondary thread to send messages to it so it can print those messages.
>
> import std.stdio;
> import std.concurrency;
>
> void main()
> {
> auto low = 0, high = 10;
>
> auto tid = spawn(&writer);
>
> foreach(i; low..high)
> {
> writeln("Main thread: ", i);
> tid.send(tid, i);
> }
> }
>
> void writer()
> {
> while( true )
> {
> receive(
> (Tid id, int i)
> {
> writeln("Secondary thread: ", i);
> }
> );
> }
> }
>
> This is the result:
> Main thread: 0
> Main thread: 1
> Main thread: 2
> Main thread: 3
> Main thread: 4
> Main thread: 5
> Main thread: 6
> Main thread: 7
> Main thread: 8
> Main thread: 9
> Secondary thread: 0
> Secondary thread: 1
> Secondary thread: 2
> Secondary thread: 3
> Secondary thread: 4
> Secondary thread: 5
> Secondary thread: 6
> Secondary thread: 7
> Secondary thread: 8
> Secondary thread: 9
> std.concurrency.OwnerTerminated@std/concurrency.d(248): Owner terminated
> ----------------
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(bool std.concurrency.MessageBox.get!(void function(std.concurrency.Tid, int)*).get(scope void function(std.concurrency.Tid, int)*).bool onControlMsg(ref std.concurrency.Message)+0x2a) [0x437016]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(bool std.concurrency.MessageBox.get!(void function(std.concurrency.Tid, int)*).get(scope void function(std.concurrency.Tid, int)*).bool scan(ref std.concurrency.List!(std.concurrency.Message).List)+0x68) [0x437084]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(bool std.concurrency.MessageBox.get!(void function(std.concurrency.Tid, int)*).get(scope void function(std.concurrency.Tid, int)*)+0x88) [0x436c20]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(void std.concurrency.receive!(void function(std.concurrency.Tid, int)*).receive(void function(std.concurrency.Tid, int)*)+0x32) [0x436b86]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(void main.writer()+0x13) [0x43066b]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(_D3std11concurrency11__T6_spawnZ6_spawnFbPFZvZS3std11concurrency3Tid4execMFZv+0x45) [0x430941]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(void core.thread.Thread.run()+0x2a) [0x4470fe]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(thread_entryPoint+0xf3) [0x446e97]
>
> The program runs correctly but then boom! Does anyone know why?
You can notify child threads that their owner terminates so they can finish up
import std.stdio;
import std.concurrency;
void main()
{
auto low = 0, high = 10;
auto tid = spawnLinked(&writer);
foreach(i; low..high)
{
writeln("Main thread: ", i);
tid.send(tid, i);
}
writeln("need to gracefully terminate child threads");
tid.send(tid, Term());
writeln("term sent");
}
struct Term {}
void writer()
{
bool done;
while( !done )
{
receive(
(Tid id, int i)
{
writeln("Secondary thread: ", i);
},
(Tid id, Term term)
{
writeln("Owner terminated, so do we");
done = true;
}
);
}
}
Main thread: 0
Main thread: 1
Main thread: 2
Main thread: 3
Main thread: 4
Secondary thread: 0
Secondary thread: 1
Secondary thread: 2
Secondary thread: 3
Secondary thread: 4
Main thread: 5
Main thread: 6
Main thread: 7
Main thread: 8
Main thread: 9
Secondary thread: 5
Secondary thread: 6
need to gracefully terminate child threads
term sent
Secondary thread: 7
Secondary thread: 8
Secondary thread: 9
Owner terminated, so do we
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June 23, 2012 Re: Strange exception using threads | ||||
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Posted in reply to Minas Mina | On 06/23/2012 09:05 AM, Minas Mina wrote: > I am using a secondary thread to send messages to it so it can print > those messages. > std.concurrency.OwnerTerminated@std/concurrency.d(248): Owner terminated The OwnerTerminated exception is thrown when a worker attempts to receive a message to notify it about the fact that its owner has been terminated. There are ways to deal with the situation: - The worker can catch this particular exception - The worker can catch this exception as a message - The owner can send a special YouAreDone :) message to the worker so it no longer attempts to receive messages and exits gracefully - More? Here is the second method as described in TDPL's concurrency chapter, which is available online: http://www.informit.com/articles/article.aspx?p=1609144 void writer() { bool done = false; while( !done ) { receive( (Tid id, int i) { writeln("Secondary thread: ", i); }, (OwnerTerminated exc) // <----- as a message { done = true; } ); } } Ali -- D Programming Language Tutorial: http://ddili.org/ders/d.en/index.html |
June 23, 2012 Re: Strange exception using threads | ||||
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Posted in reply to simendsjo | On Sat, 23 Jun 2012 18:29:37 +0200, simendsjo <simendsjo@gmail.com> wrote:
> auto tid = spawnLinked(&writer);
auto tid = spawn(&writer); of course
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June 23, 2012 Re: Strange exception using threads | ||||
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Posted in reply to Ali Çehreli | On Sat, 23 Jun 2012 18:29:50 +0200, Ali Çehreli <acehreli@yahoo.com> wrote:
> receive(
> (Tid id, int i)
> {
> writeln("Secondary thread: ", i);
> },
> (OwnerTerminated exc) // <----- as a message
> {
> done = true;
> }
> );
Nice. I thought you had to send an explicit message.
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June 23, 2012 Re: Strange exception using threads | ||||
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Posted in reply to simendsjo | Thank you very much :) I like the "you are done :)" approach! |
June 24, 2012 Re: Strange exception using threads | ||||
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Posted in reply to simendsjo | On Jun 23, 2012, at 9:31 AM, simendsjo <simendsjo@gmail.com> wrote:
> On Sat, 23 Jun 2012 18:29:37 +0200, simendsjo <simendsjo@gmail.com> wrote:
>
>> auto tid = spawnLinked(&writer);
>
> auto tid = spawn(&writer); of course
With spawnLinked the child will send a termination message to the parent as well.
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